The Ruwanweli Seya, constructed in the 2nd century B.C. by Emperor Dutugamunu, is without a doubt the greatest of the of the dagobas at Anuradhapura. Of the eight sites in Anuradhapura that are sacred to the Sri Lankan Buddhists, Ruwanweli Seya ranks second. Only the Sri Maha Bodhi is considered more sacred. In popularity however, among the Sri Lankans as well as among the visiting tourists, Ruwanweli Seya leads the way by a considerable margin. The original stupa was modeled in the shape of a pure "water bubble". On the south-west side of the compound there is a small dagoba that has this shape. This may have been used as a model for the great stupa. The larger-than-life statue of the dignified man, respectfully watching the dagoba is considered to be Dutugmunu himself.
On the west side of the compound, Basawakkulama tank dates back to the 4th century B.C. and is probably the oldest tank in Sri Lanka. The Thuparama Dagoba, north of the Ruwanweli Seya is considered to be the oldest dagoba in Sri Lanka. It is popularly believed that the collar bone of Lord Buddha is enshrined within this dagoba.